求 2sin0+cosπ+根号2cos(-π/4)-tanπ/4的值

问题描述:

求 2sin0+cosπ+根号2cos(-π/4)-tanπ/4的值
还有一题已知sinθ=3/5,θ∈(π/2,π).求cosθ

2sin0+cosπ+根号2cos(-π/4)-tanπ/4的值
=0-1+根号2*根号2/2-1
=-1+1-1
=-1
已知sinθ=3/5,θ∈(π/2,π).第二象限,cosθ